(1) Field of the Invention
The present invention relates to a data backup device and method suitable for use with a computer and to a computer-readable recording medium having a data backup program recorded thereon.
(2) Description of the Related Art
In recent years, computers, such as personal computers, as well as computer networks dominantly comprising Internet and personal computer communication, have become prevalent. In association with this tendency, important data sets such as electronic mail or documents stored in a storage device of a computer have also increased.
The contents of the important data sets may be destroyed or become unavailable by the user""s faulty operation of the computer or by a breakdown in the storage device. The loss of data results in significant damage in terms of time and money.
In a method of minimizing damage by immediately recovering a data file in the event of problems such as the loss of data, a technique of duplicating information (i.e., a data backup technique) becomes important.
As shown in FIG. 18, a computer 50 comprises a predetermined storage device 51 and a backup storage device 52. Data which are identical to the data stored in the storage device 51 are stored in the storage device 52, thereby preventing the foregoing damage.
With regard to common data backup methods, there are various data backup methods which vary among the types of data files to be reproduced (or copied) and the ways the data files are input or output. Each of the methods will now be described.
(a) Data backup methods varying with the types of data files to be copied
These data backup methods are classified into three methods according to the type of data file to be copied; that is, a full backup method, a differential backup method, and an incremental backup method.
(a1) Full Backup Method
According to this method, all the data files stored in an area in storage to be copied are copied at one time.
(a2) Differential Backup Method
According to this method, among the data files stored in an area in storage to be copied, the data files copied are those whose data have been updated or which have been newly created since the last backup version was created by full backup.
(a3) Incremental Backup Method
According to this method, among the data files stored in an area in storage to be copied, only the data file copied are those whose data have been updated or which has been newly created since the last backup version was created by full backup or differential backup.
(b) Data backup methods varying with the ways a data file is input or output
The processing time required for the data backup method is determined by a method of inputting or outputting a data file required when the data file is copied. The inputting and outputting of one data file involves open processing, read/write processing, and close processing. With reference to FIG. 19, an explanation will be given of copying of a file A stored in the storage device 51 (for holding the original file) to a file Axe2x80x2 stored in the storage device 52 (for holding a copied file).
More specifically, the open processing is a process for making a data file available by extraction of information about the data file; e.g., the location of the data file in the storage device, the date on which the file was created, or the size of the data file.
The read/write processing is a process for reading contents from or into a data file and is designed to write the data read from the file A to the file Axe2x80x2. The close processing is a process for terminating utilization of a data file and is designed to discard information about the data file extracted at the time of open processing.
The following explanation describes the three types of data backup methods that vary with the file input-output processing methods.
(b1) Data Backup Method Utilizing Disk Image
Under this method, data are directly read from the storage device and written on another storage device without regard to a data structure configured in the storage device. For example, as shown in FIG. 20, raw data stored in the storage device 51 are stored in the storage device 52, exactly as they are.
Since this method disregards the data structure configured in the storage device, there is no need to execute open/close processing for the purpose of inputting or outputting data on a file-by-file basis, thus resulting in a reduction in processing time.
(b2) Data Backup Method Utilizing File Image (1)
Under this method, data are read on a file-by-file basis, and the thus-read data are written into another storage device on a file-by-file basis according to the data structure configured in the storage device. For example, as shown in FIG. 21, data concerning files A, B, and C stored in the storage device 51 are stored, respectively, in the storage device 52 on a file-by-file basis.
In short, this method enables data to be copied or restored on a file-by-file basis according to the data structure configured in the storage device and can be applied to the foregoing differential or incremental backup method.
(b3) Data Backup Method Utilizing File Image (2)
Under this method, data are read on a file-by-file basis according to the data structure configured in the storage device, and the thus-read data files are grouped into one data file. The data files are written into another storage device on a file-by-file basis. For example, as shown in FIG. 22, all the data sets concerning the files A, B, and C stored in the storage device 51 are collectively stored in the storage device 52.
This method enables data to be copied or restored on a file-by-file basis according to the data structure configured in the storage device. Further, since this method permits the data files read from the storage device 51 to be grouped into one data file and to be written into the storage device 52, execution of the open and close processing is required to be performed only once, collectively, in order to write the data files into the storage device 52.
More specifically, many commercially-available data backup software packages employ the foregoing method (b2). For example, a backup software package bundled with MS-Windows 95, which is commercially available from Microsoft Co., Ltd. and is an operating system (OS) for use in a personal computer, employs the data backup method (b2). In addition, ASCserver and Cheyenne Backup, which are available from Computer Associates Ltd., and Seagate Backup, which is available from Seagate Co., Ltd., also employ the foregoing method (b2).
In a case where user data comprising electronic mail or documents are copied in a personal computer which uses a 32-bit Pentium microprocessor of 90 MHz, through use of the backup software package bundled with MS-Windows 95, the processing rate determined from the processing time required to copy the data by measurement is 185 KB/s.
The foregoing data backup methods suffer the following problems. First, as mentioned previously in section (a) entitled xe2x80x9cData backup methods varying with the types of data files to be copied,xe2x80x9d under the differential or incremental backup method, if data are copied several times, there are required recording mediums having backup operations or backup data files recorded thereon in the number corresponding to the number of times the data are copied, resulting in an increase in the number of recording mediums. Further, in this case, when the copied data files are restored, they must be restored in the order in which they were copied.
To solve the foregoing problem, the number of backup data files or recording mediums must be reduced, and the copied data files must be restored in a simple manner. Accordingly, all the data files must be copied after the differential or incremental backup operation has been performed for a given period of time. In order to reduce the overall processing time required by a data backup system, the processing time required for the full backup operation must be reduced.
Next, in the case of data backup method (b1) utilizing a disk image described in section (b) entitled xe2x80x9cData backup methods varying with the ways a data file is input or output,xe2x80x9d since the data structure is disregarded, data cannot be copied on a file-by-file basis, which in turn makes it impossible to perform the differential or incremental backup operation. Further, the method involves reading of a null data set from an empty area in the storage device 51 and writing of the thus-read null data set to the other storage device 52, causing waste of resources.
In the case of data backup method (1) utilizing a file image referred to in section (b2), each of the storage device 51 (holding the original file) and the storage device 52 (holding a copied file) must open and close a data file on a file-by-file basis, requiring a longer processing time as compared with that required by method (b1).
In the case of data backup method (2) utilizing a file image referred to in section (b3), a data file is opened and closed once for each data file. Therefore, the processing time required by method (b3) can be reduced in comparison with that required by method (b2), but still remains longer than that required by method (b1).
The present invention has been contrived in view of the foregoing drawbacks in the art, and an object of the present invention is to provide a data backup device and method for use with a computer that enables efficient copying of a data file in a short period of time by making improvements in a data file to be copied.
Another object of the present invention is to provide a computer-readable recording medium having a data backup program for the purpose of performing the foregoing data backup operation recorded thereon.
To these ends, according to one aspect of the present invention, there is provided a data backup device for use with a computer which stores data files stored in a first storage section into a second storage section in a duplicated manner, the device comprising: a selection section for selecting data files satisfying given conditions from among the data files stored in the first storage section; an archive file creation section which creates N (N is a natural number) archive files by grouping the plurality of data files selected by the selection section and which repeats the archive file creation processing M (M is a natural number) times; and a backup processing section which stores the archive files created by the archive file creation section into the second storage section.
Since the data backup device according to the present invention groups the data files to be copied into archive files before the data files are copied, the time required to copy the data files can be reduced. Hence, the present invention yields the advantage of enabling significant improvements in the processing capability of the data backup device. Further, since the data backup device uses distributed processing to cause the archive file creation section to create an archive file and to cause the backup processing section to copy the thus-created archive file, the processing operations can be performed speedily and accurately, thus increasing the processing rate of the data backup device.
Preferably, in the data backup device according to the present invention, the selection section is configured to select a data file of a given size or smaller.
Since the data backup device according to the present invention is configured in such a way that the selection section selects a data file of a given size or smaller, the processing time and the size of the archive file to be stored can be limited. Accordingly, the storage capacity of the first storage section can be reduced.
Preferably, in the data backup device according to the present invention, the selection section is configured in such a way that when the archive file creation section is performing the mth operation (where xe2x80x9cmxe2x80x9d is a natural number satisfying mxe2x89xa6M), the selection section selects only those data files which have been modified or newly created since the archive file creation section performed the Mxe2x88x921th operation.
Since the data backup device according to the present invention is configured in such a way that the selection section selects only those data files which have been modified or newly created since the archive file creation section created an archive file in the preceding processing, the number of data files to be grouped can be reduced, and the number of archive files can also be reduced. In this case, the backup processing rate of the data backup device can be increased.
Preferably, in the data backup device according to the present invention, the selection section is configured in such a way that when the archive file creation section is performing the mth operation (where mxe2x89xa6M), the selection section selects only those data files which have been modified or newly created since the archive file creation section performed the first operation.
Since the data backup device according to the present invention is configured in such a way that, in a case where the number of archive files is increased, the selection section extracts the archive files created when the archive file creation section has performed the first operation and selects only the data files which have been modified or newly created since the archive file creation section performed the first operation, the number of data files to be grouped can be reduced. In this case, the number of archive files can be reduced.
Preferably, in the data backup device according to the present invention, the archive file creation section is configured in such a way that, after having created an archive file, the archive file creation section compresses the thus-created archive file.
Since the data backup device according to the present invention is configured so as to compress the created archive file, the size (amount of data) of the archive file to be stored can be reduced. The present invention yields the advantage of being able to reduce storage capacity of the first storage section for creating archive files or that of the second storage section for storing copied archive files or data files.
Preferably, in the data backup device according to the present invention, the archive file creation section is configured in such a way that, after having compressed each of data files, the archive file creation section creates archive files.
Since the data backup device according to the present invention is configured so as to create archive files after having compressed each of data files to be copied, data files can be newly added to the archive files without decoding the archive files, whereby archive files can created speedily.
Preferably, in the data backup device according to the present invention, the archive file creation section is configured in such a way that the archive file creation section adds the data file selected by the selection section during the mth operation (where mxe2x89xa6M) of the archive file creation section to the archive files created during the mxe2x88x921th operation of the same.
Since the data backup device according to the present invention is configured so as to add the data file to be newly updated to the archive file that has been created in the preceding grouping operation, the present invention yields the advantage of being able to create archive files by an extremely simple operation; that is, by addition of a data file to archive files.
Preferably, in the data backup device according to the present invention, the archive file creation section is configured in such a way that, after having deleted a past data file corresponding to a data file to be updated from the archive files, the archive file creation section adds the data file selected by the selection section during the mth operation (where mxe2x89xa6M) of the archive file creation section to the archive files created during the mxe2x88x921th operation of the same.
Since the data backup device according to the present invention is configured so as to delete a data file corresponding to a data file to be updated when a data file to be newly updated is added to the archive file that has been created in the preceding grouping operation, the amount of storage of the archive files can be reduced, and only the newest information can be copied to the second storage section.
Preferably, in the data backup device according to the present invention, the backup processing section is configured to store into the second storage section the archive files and those data files that have failed to satisfy given conditions.
Since the data backup device according to the present invention is configured so as to group data files to be copied into archive files before the data files are copied, the present invention yields the advantages of being able to reduce the time required to copy the data files and being able to significantly improve the processing capability of the data backup device. Further, since the data backup device uses distributing processing in performing the creation of an archive file in the archive file creation section and in copying the thus-created archive files in the backup processing section, the processing operations can be perform speedily and accurately, thereby increasing the processing rate of the data backup device.
Preferably, in the data backup device according to the present invention, the backup processing section is configured to compress the archive files and those data files that have failed to satisfy given conditions and then store the thus-compressed files into the second storage section.
Since the data backup device according to the present invention is configured so as to compress the archive files and the data files that have failed to satisfy given conditions when these files are copied to the second storage section, the present invention yields the advantages of being able to reduce the load exerted on the archive file creation section when the archive file creation section repeatedly creates archive files and being able to reduce the storage capacity of the second storage section to which the data files are copied.
Preferably, in the data backup device according to the present invention, the backup processing section is configured in such a way that, after having added to the archive files, another archive file or those data files that have failed to satisfy given conditions, the backup processing section stores the archive files into the second storage section.
Since the data backup device according to the present invention is configured so as to copy the archive files after the addition to the archive files or another archive file or those data files that have failed to satisfy given conditions, the number of files to be copied can be reduced. In this case, the present invention yields the advantage of being able to improve the copying capability of the data backup device.
Preferably, in the data backup device according to the present invention, the backup processing section is configured in such a way that, after having grouped into another archive file the archive files and those data files that have failed to satisfy given conditions, the backup processing section stores the thus-grouped archive files into the second storage section.
Since the data backup device according to the present invention is configured so as to copy the archive files and those data files that have failed to satisfy given conditions after these files have been grouped into another archive file, the user can speedily extract data on a per-unit basis easily available for the user.
Preferably, in the data backup device according to the present invention, the backup processing section is configured in such a way that the backup processing section causes the archive file creation section to create an archive file one time immediately before copying to the second storage section the archive files and those data files that have failed to satisfy given conditions.
Since the data backup device according to the present invention is configured in such a way as to allow the archive file creation section to create an archive file one time immediately before the archive files and those data files that have failed to satisfy given conditions are copied to the second storage section, the newest data file can be copied without fail, contributing to improvements in the performance of the data backup device.
According to another aspect of the present invention, there is provided a data backup method for use with a computer which stores the data files stored in a first storage section into a second storage section in a duplicated manner, the method comprising the steps of: selecting data files that satisfy given conditions from among the data files stored in the first storage section; creating N (N is a natural number) archive files by grouping the plurality of selected data files; and storing the archive files into the second storage section after having repeatedly performed the data file selection and the archive file creation M (M is a natural number) times.
Since the data files to be copied are grouped into archives before the data files are copied under the data backup method according to the present invention, the time required to copy the data files can be reduced. Hence, the present invention yields the advantage of being able to significantly improve the processing capability of a data backup device. Further, under this method, since distributed processing is used to cause the archive file creation section to create an archive file and to cause the backup processing section to copy the thus-created archive file, the processing operations can be performed speedily and accurately, thus increasing the processing rate of the data backup device.
According to still another aspect of the present invention, there is provided a computer-readable recording medium on which is recorded a data backup program for activating a computer in order to store the data files stored in a first storage section into a second storage section in a duplicated manner, the program comprising: a selection function of selecting from among the data files stored in the first storage section those data files that satisfy given conditions; an archive file creation function of creating N (N is a natural number) archive files by grouping the plurality of selected data files and repeating the archive file creation processing M (M is a natural number) times; and a backup processing function of storing the thus-created archive files into the second storage section.
Since, before being copied, the data files to be copied are grouped into archives by means of the computer-readable recording medium having a data backup program recorded thereon according to the present invention, the time required to copy the data files can be reduced. Hence, the present invention yields the advantage of being able to significantly improve the processing capability of a data backup device. Further, under this method, since distributed processing is used to cause the archive file creation section to create an archive file and to cause the backup processing section to copy the thus-created archive file, the processing operations can be performed speedily and accurately, thus increasing the processing rate of the data backup device.